Electric vehicles and/or those operable with muscle power are available in various embodiments. With such vehicles, it is often desirable to ascertain a twisting moment or torque acting on a shaft. The magnetostriction effect, magnetoelasticity effect, or inverse magnetostriction or magnetoelasticity effect can be utilized in this context. This effect is based on the deformation of magnetic, in particular ferromagnetic, substances as a result of an applied magnetic field. A corresponding body experiences, at constant volume, an elastic change in length. With inverse magnetostriction or magnetoelasticity, conversely, the magnetic properties are modified by an impressed change in length or shape.
This can be utilized in order to determine the torque that is acting on a shaft. For this, a portion of the shaft is configured with or from a material that exhibits the inverse magnetostriction or magnetoelasticity effect.
It is problematic, however, that a specific distance exists between that portion of the shaft and a sensor that is intended to measure the magnetic field and the change therein, since the sensor is disposed, along with a sensor holder, outside the shaft that is to be measured. If the sensor and sensor shaft, i.e. the shaft whose torque or torsional moment is to be determined and which is correspondingly configured with the magnetostrictive material, are not oriented in consistently concentric fashion with respect to one another, static measurement deviations in the sensor signal can then occur due to a differing distance or air gap between the sensor and sensor shaft.
In addition, dynamic errors can also occur due to errors in the concentricity and coaxiality of the shaft, and can negatively influence the sensor signal and the evaluation thereof.